Tool for a prosthetic part

ABSTRACT

A tool is described, which is intended for screwing into place a threaded prosthetic part (6). The tool comprises a turning bolt (1) which has an elongated cylindrical core (2) having at one end thereof a head (3) for turning the tool, and having at its opposite end a portion (4) first threads (5) for fitting into threads in the prosthetic part, and is characterized in that the core has second threads (11), on a portion (10) thereof between the ends thereof, said second threads having a pitch direction opposite to the pitch direction fo the first threads, and a sleeve (13) arranged around the core, said sleeve having threads engaging said second threads, whereby the sleeve may be screwed into contact with the prosthetic part (6) locking the tool in the prosthetic part.

TECHNICAL FIELD

The present invention is related to a tool for screwing into place athreaded prosthetic part (6), such as a part of a dental implant. Theobject of the invention is to provide a tool by which a prosthetic parthaving no grip means may be gripped, screwed into place and releasedfrom the tool in a simple manner.

STATE OF THE ART

From Adell et al., Int. J. Oral Surg. 10 (1981) page 388 a dentalimplant system is known comprising a root screw or fixture (a), adistance screw (d) and a gold cylinder (k). The root screw is intendedto be screwed into a hole taken up in the jaw bone of a patient, and thedistance screw is intended to be screwed into a hole in the root screw.For screwing into place, the root screw and the distance screw are bothprovided, at the upper ends thereof, with projecting hexagonal wrenchabutments which may be gripped with a wrench having a correspondingrecess. The making of such wrench abutments is a cost-raisingfine-mechanical work operation in manufacture of said parts. The wrenchabutments further have to be covered by the vaulted head of a screw or aplastic cap in order not to irritate the tissues of the oral cavity.

From WO No. 85/02337 an implant system is known comprising a root screw1 and a pillar 6, neither of which having special grip means. For quickand easy attachment of said parts there is, however, a need for a tool.

DESCRIPTION OF THE INVENTION

According to the present invention there is provided a tool of the kindreferred to initially above, which fulfils the object presented above.The tool comprises a turning bolt which has an elongated cylindricalcore having at one end thereof a head for turning the tool, and havingat its opposite end a portion with first threads for fitting intothreads in the prosthetic part. The tool is characterized in that thecore has second threads on a portion thereof between the ends thereof,said second threads having a pitch direction opposite to the pitchdirection of the first threads, and a sleeve arranged around the core,said sleeve having threads engaging said second threads, whereby thesleeve may be screwed into contact with the prosthetic part and to lockthe tool in the prosthetic part.

The tool is primarily intended for screwing into place a part of adental implant, such as root screw which is screwed into a hole taken upin the jaw bone, or another part, which in turn is to be attached to theroot screw, e.g. a distance element. The first threads should have thesame pitch direction as the threads by which the prosthetic part isscrewed into its place of attachment. For all practical purposes, allthese threads are normal right-handed threads, which means that thesecond threads arranged on the tool are left handed threads.

According to a preferred embodiment of the invention, the tool ischaracterized in that the second threads are arranged on a portion ofthe core having a greater diameter than the threaded end, and that thesleeve arranged around the core has a main portion in which the threadsare arranged, and an end portion having a reduced diameter adjacent tothe threaded end portion of the core.

The end of the sleeve adjacent to the threaded end of the core has acontact surface shaped for fitting against the prosthetic part to bescrewed into place. The contact surface of the socket may thus be e.g.planar, inwardly conical or outwardly conical.

The invention will be further described with reference to the appendeddrawings, wherein:

FIG. 1 is an exploded view showing a tool according to the inventiontogether with prosthetic parts and a connector,

FIG. 2 is a side view of a turning bolt for the tool in FIG. 1,

FIG. 3 shows a sleeve, partly in section, for the tool in FIG. 1, and

FIG. 4 shows a tool according to the invention at an oblique view fromabove.

In the drawings 1 denotes a turning bolt having an elongated cylindricalcore 2 with a head 3 at one end thereof. The opposite end of the corehas a cylindrical portion 4 having at the outer end thereof outwardright-handed threads 5, which in FIG. 1 are in engagement with fittinginward threads in a pillar 6 serving as a distance element, which pillaris intended to carry a dental prosthesis. The pillar has, at theopposite end thereof, a cylindrical portion 7 provided with outwardright-handed threads 8 by which it may be screwed into correspondingthreads in a root screw 9. The root screw 9 in turn has outwardright-handed threads by which it may be screwed into andosseo-integrated in a hole bored in the jaw-bone of a patient.

The core 2 of the turning bolt has a portion 10 adjacent to the head,which portion has a greater diameter than the end portion 4 and which isprovided with outward left-handed threads fitting into correspondinginward threads 12 in a sleeve 13. The threads 12 are cut in the mainportion 14 of the sleeve having on its outer surface two cut-recesses15.

Via a conical portion 16 the main portion continues into an end portion17 having reduced diameter, wherein the inner diameter is only slightlygreater than the diameter of the threaded end portion 4 of the core. Thesleeve has a planar end surface 18 by which it rests against the end ofthe pillar 6. In the upper end surface of the head of the turning bolt,there is a hexagonal recess 19, which may be put into engagement withthe hexagonal head 20 of a connector 21 having at its opposite endattachment means 22 for an angled head of a dentist's boring machine.Further, the cylindrical surface of the head is knurled to facilitatemanual turning thereof. Similarly, the cylindrical outer surface of thesleeve is knurled.

Although the tool is shown designed for screwing a pillar into place, itis obvious that the tool may be designed, through dimensionaladjustment, for screwing another prosthetic part, such as a root screw 9into place.

In use, the end 4 of the turning bolt is screwed into the prostheticpart to a position where the threads 5 are securely engaged in the holeof the pillar while the end does not reach the bottom thereof. Thesleeve is brought into contact, by left-hand turning (anti-clockwise),via its end surface 18 against the pillar. The tool is gripped by thehead thereof and the prosthetic part is screwed in a few revolutionsinto the root screw. If desired the turning may be continued via theconnector 21 and a boring machine. Thereupon, the tool is released byleft-handed turning, whereby the sleeve may be held by a wrench engagedover the cut recesses 15.

The tool according to the invention may also be used for releasing aprosthetic part, whereby the tool will be gripped and turned via thesleeve 13.

The tool may be manufactured by lathing of a metal such as stainlesssteel or titanium.

I claim:
 1. A tool for screwing into place a threaded prosthetic part(6), which tool comprises a turning bolt (1) which has an elongatedcylindrical core (2) having at one end thereof a head (3) for turningthe tool, and having at its opposite end a portion (4) with firstthreads (5) for fitting into threads in the prosthetic part, and havingsecond threads (11) on a portion (10) thereof between the ends thereof,whereby a sleeve (13) is arranged around the core, said sleeve havingthreads engaging said second threads, whereby the sleeve may be screwedinto contact with the prosthetic part (6) and to locking of the tool inthe prosthetic part, characterized in the pitch direction of said secondthreads is opposite to the pitch direction of the first threads.
 2. Atool according to claim 1, characterized in that the second threads arearranged on a portion (10) of the core having a greater diameter thanthe threaded end portion (4) of the core, and that the sleeve (13)arranged around the core has a main portion in which the threads (12)are arranged, and an end portion (17) having a reduced diameter adjacentto the threaded end portion of the core.